The invention relates to a device for blocking or releasing the flow-through of a gaseous or liquid medium and, more particularly, to a valve in which a ball is positioned in a conical or spherical valve seat and is movable relative to the seat by means of a release bar.
In known devices of this type, the releasing rod acts on the ball, urging it in a direction opposite the direction in which the ball is moved by the fluid pressure. This is somewhat disadvantageous in that the force required to lift the valve ball from the seat must exceed a certain threshold force. Typically, this threshold force is substantial and, therefore, prior art valves have necessarily been relatively large and have required powerful drives.
It is seen that there is a need, therefore, for a valve device of the above-described type which requires a relatively small releasing force.